Stirring the mash is not a good idea if you are looking for consistency. I introduces oxygen to your mash, which , i think makes the finished product unstable, loosing flavors prematurely.
I built a RIMS and get excellent results. I built a heat source using a piece of 1.5" copper pipe; a hot water heater element and a PID/relay from Omega engineering. Set and forget till its time to raise to your next rest, never overshoot your mash temp.
A good read can be found at theelectricbrewery.com. The author discusses building an electric HERMS, but you can modify to RIMS and has plenty of other ideas you might find helpful.
Thanks for the link. Eventually, I may consider an automated mash system, but I'm not really interested in using a HERMES/RIMS at the moment because I primarily do single infusions. I think an automated system would be great for multi step infusions.
How do you return the wort to your mash tun after it leaves the heating tube, and how fast can you ramp temps from a sach rest to mash out?
I find if I don't stir, I don't get uniform temp over the mash tun. Plus, I only stir for a minute or so, not the entire mash duration. Also, I don't worry about oxidation during the mash because dissolved oxygen is lower at mashing temperatures, the low mash pH environment should help minimize any potential oxidative effects, and the boil will essentially remove most of the dissolved oxgen, which doesn't leave a lot of residence time for the oxygen to start oxidizing compounds.